Line Strengths Research Articles

A Wide Metallicity Range for Gyr-old Stars in the Nuclear Star Cluster

We report metallicities for three ∼Gyr-old stars in the Milky Way nuclear star cluster (NSC) using high-resolution near-infrared spectroscopy. We derive effective temperatures from a calibration with Sc line strength, which yields results in good agreement with other methods, and metallicities from spectral fits to Fe i lines. Our derived metallicities range from −1.2 < [Fe/H] < + 0.5, a span of 1.7 dex. In addition we use isochrone projection to obtain masses of 1.6–4.3 M ⊙, and ages assuming single-star evolution. The oldest of these stars is 1.5 Gyr while the youngest and most metal-rich is only 100 Myr. The wide range in metallicity poses interesting questions concerning the chemical evolution and enrichment of the NSC and adds to the evidence for the presence of a young, metal-rich population in the NSC. We suggest that the candidate intermediate-age, metal-poor ([Fe/H] = −1.2) star may be best explained as a blue straggler from an underlying old population.

Application of Laser Treatment in Adhesive Bonding of Liners to Polymethyl Methacrylate Denture Resins: A Systematic Review and Meta-Analysis.

Objective: This systematic review and meta-analysis aimed to assess the influence of laser treatment on adhesive bonding of liners to polymethyl methacrylate (PMMA) denture base resins. Methods: The focused question was: "Does the application of laser treatment (Intervention) influence the adhesive bonding strength (Outcome) of liners to PMMA denture base resins (Population) as compared with untreated or unconditioned surfaces (Control)?" In vitro and clinical reports as well as reports on influence of laser treatments on bonding strength of liners to PMMA denture resins in comparison with untreated surfaces were included. Reports without any control group[s], without any application of laser[s] for PMMA denture bases that did not utilize PMMA denture bases, and not evaluate bond strength of PMMA denture base resins were excluded. An electronic search was conducted on PubMed, Scopus, and Web of Science. Meta-analyses were performed for calculating the standard mean difference (SMD) with a 95% confidence interval (95% CI). Results: Nine of the 12 included studies found that laser irradiation treatment produced significant surface texture alterations of the PMMA denture base and improved the adhesion between the PMMA denture base and soft lining. According to the meta-analysis, tensile bond strength showed an SMD of -2.49% (95% CI: -3.89 to -1.08; p = 0.0005), suggesting a statistically significant difference between the control and test groups (i.e., favoring laser-treated samples than untreated samples). Regarding shear bond strength scores, the outcomes showed an SMD of -2.24% (95% CI: -3.79 to -0.69; p = 0.005), suggesting a statistically significant difference between the control and test groups (i.e., favoring laser-treated samples than untreated samples). Conclusions: Despite the high heterogeneity among the included studies, it can be concluded that laser treatment might improve the bonding strengths of liners to PMMA denture base resins as compared with untreated surfaces. To validate the aforementioned conclusions, further verification is required through the implementation of well-designed randomized controlled trials with large sample sizes.

Interference-free laser-based temperature and CO-concentration measurements for shock-heated isooctane and isooctane/ethanol blends

Species concentration (e.g. CO) and temperature measurements in the combustion field require fast-response technique without interfering species. In the last decade, tunable diode lasers have been established as strong technique to measure species such as CO, CO2, and H2O as well as temperature with high sensitivity. The drawback is the degree of interference that might hamper the robustness of the technique. In this work simultaneous measurements of temperature and CO concentration were carried out using an interference-free mid-infrared laser-based absorption technique behind reflected shock waves. Two transition lines of CO (P(v″ = 0, J″ = 21) and P(v″ = 1, J″ = 21)) in the fundamental vibrational band near 4.87 and 4.93 μm, respectively, were selected. Absorbance interferences from CO2 and H2O at room and high temperatures were evaluated. Spectroscopic parameters for the development of the system were measured: line strengths and collisional broadening coefficients (in Ar) of both lines were obtained at 1020–1950 K by using the scanned-wavelength direct-absorption method. The technique was demonstrated for non-reactive and reactive mixtures. For the non-reactive case, temperature and CO concentration were measured at 1030–1910 K and 1.0–3.7 bar. For the reactive case, oxidation of i-C8H18/O2/Ar and i-C8H18/C2H5OH/O2/Ar mixtures were investigated at three equivalence ratios of 2.0, 1.0, and 0.5. The two newly adopted lines exhibited good performance in the detection of CO concentration and are immune to interferences from CO2 and H2O. In addition, the simulated data from the state-of-the-art isooctane/ethanol mechanisms in literature were compared with the measured data, showing overall good agreement.

Weld Line Strength of Polyamide Fiberglass Composite at Different Processing Parameters in Injection Molding Technique.

This study examines the impact of injection parameters on the weld line strength of the polyamide 6 and 30% fiberglass (PA6 + 30% FG) composite samples. The effects of filling time, packing time, packing pressure, melt temperature, and mold temperature on the ultimate tensile strength (UTS) and the elongation value of the weld line are investigated. The results reveal that the filling time factor has the lowest influence rate. On the contrary, the packing pressure has the most considerable value of UTS standard deviation, indicating that this factor has a high impact rate. The melt temperature factor has the highest elongation standard deviation, pointing out the strong impact of melt temperature on the elongation value. In reverse, the filling time factor has the lowest elongation standard deviation, showing the low impact of this factor on the elongation value. Increasing the mold temperature enhances the elongation value greatly because a higher temperature generates a better connection in the weld line area. Although the UTS value improves modestly when the mold temperature control system is used, the elongation result from the mold temperature parameter is better than expected. The UTS result from all parameters presents a minor deviation; therefore, it is lower than expected. The optimal strength result from artificial neural networks with genetic algorithm optimization is 85.1 MPa, which is higher than the best experiment result of 76.8 MPa. Scanning electron microscopy (SEM) results show that the interface between the fiberglass and the PA matrix has high adherence. The fracture surface is smooth, indicating that the PA6 + 30% FG composite sample has a high fragility level. The findings could help to increase the injection sample's weld line strength by optimizing the injection molding conditions.

Modified pine needles as a formaldehyde scavenger for urea-formaldehyde resin in plywood production

The aim of the present work was to investigate whether it is possible to use ground pine needles as formaldehyde-scavenging filler for urea-formaldehyde resin in the production of plywood. The scope of the research included determinations of both optimal amount of introduced filler and the effect of its modification (silanization, hydrothermal and alkaline treatments). Properties of adhesives such as viscosity, gel time and pH were investigated and their morphology was assessed using scanning electron microscopy. The manufactured plywood panels were tested in terms of their wet shear strength, tendency to delamination in varying conditions and formaldehyde emission. It was found that the addition of pine needles lowers the pH and reduces gel time of the adhesive. Moreover, it was shown that despite the significant reduction in formaldehyde emission, the addition of non-modified needles causes a decrease in bonding quality of plywood. Based on the results, 10 parts by weight of needles per 100 parts by weight of resin can be considered as an optimal loading. The use of ground needles modified hydrothermally and with silane allows to minimize the negative effect on the strength of glue lines and leads to further reduction of formaldehyde emission. Therefore, it can be concluded that pine needle powder has strong potential for the application as a formaldehyde-scavenging filler for urea-formaldehyde adhesive in plywood production.

High-resolution Spectroscopy of SN 2023ixf’s First Week: Engulfing the Asymmetric Circumstellar Material

We present a series of high-resolution echelle spectra of SN 2023ixf in M101, obtained nightly during the first week or so after discovery using PEPSI on the Large Binocular Telescope. Na i D absorption in these spectra indicates a host reddening of E(B − V) = 0.031 mag and a systemic velocity of +7 km s−1 relative to the average redshift of M101. Dramatic changes are seen in the strength and shape of strong emission lines emitted by circumstellar material (CSM), including He ii λ4686, C iv λλ5801,5811, Hα, and N iv λλ7109,7123. In general, these narrow lines broaden to become intermediate-width lines before disappearing from the spectrum within a few days, indicating a limited extent to the dense CSM of around 20–30 au (or ≲1014.7 cm). Hα persists in the spectrum for about a week as an intermediate-width emission line with P Cyg absorption at 700–1300 km s−1 arising in the post-shock shell of swept-up CSM. Early narrow emission lines are blueshifted and indicate an expansion speed in the pre-shock CSM of about 115 km s−1, but with even broader emission in higher-ionization lines. This is faster than the normal winds of red supergiants, suggesting some mode of eruptive mass loss from the progenitor or radiative acceleration of the CSM. A lack of narrow blueshifted absorption suggests that most of the CSM is not along our line of sight. This and several other clues indicate that the CSM of SN 2023ixf is significantly aspherical. We find that CSM lines disappear after a few days because the asymmetric CSM is engulfed by the supernova photosphere.

Effect Of Montmorillonite Incorporation on Shear Bond Strength And Surface Hardness Of Acrylic Base Soft Lining Material (In Vitro Study)

Abstract Objective: One problem with the soft lining material is that it detaches from the acrylic base of dentures after a particular time period. So, the aim of this work was to evaluate how adding Montmorillonite nano clay would affect the soft lining material's shear bond strength and surface hardness. Materials and Methods: The heat-cured acrylic denture material for the control group, polymer reinforced with (0.25%,0.5% by wt.) of montmorillonite nanoparticles for experimental groups was used in this study. For the shear bond strength test 60 blocks of acrylic-based material were constructed, each pair connected with soft lining material, the other 30 specimens for the surface hardness tests were carried out. to be tested with a shore A durometer. The data were statistically examined using the One-Way ANOVA test and Bonferroni multiple comparisons test. Result: 0.5% by weight MMTNPS should significantly increase in both shear bonding strength and surface hardness . Conclusion: MMTNPs were remarkably successful in improving the the strength of the shear connection between acrylic and soft liners.

High toughness of nanotwinned copper lines after annealing

High toughness and tensile strength are favorable factors to advance the applications of Cu lines. In this study, 60-μm-wide nanotwinned Cu (NT-Cu) and regular Cu lines were electroplated and further heat-treated. The annealing-induced effect on the mechanical properties was then investigated. Results showed that the tensile strength of the NT-Cu lines was apparently greater than that of the regular Cu counterparts. Under annealing, the tensile strength of the NT-Cu lines dropped slightly due to thermal-induced detwinning effect. However, such a heat treatment at 150 °C for 3 h greatly enhanced their elongation (7.0%–13.4%) and toughness (32.0 MJ/m3 to 64.9 MJ/m3). No obvious grain growth was observed in the NT-Cu after annealing at 250 °C for 3 h. Meanwhile, grain coarsening occurred in the regular Cu lines leading to significant decrease in the tensile strength, and their toughness was only 6.6 MJ/m3 after the annealing at 150 °C for 3 h. Additionally, the microstructures of the NT-Cu were analyzed by transmission electron microscopy and electron backscattered diffraction. Hall-Petch equation and confined layer slip (CLS) model were also employed to estimate and correlate the yield strength of the NT-Cu lines with twin spacing and average grain size.

Relativistic atomic structure calculations for B-like xenon ion

Excitation energies, transition parameters and lifetimes for 255 levels with n≤ 4 configurations of B-like Xe49+ are calculated using the fully relativistic multiconfiguration Dirac–Hartree–Fock (MCDHF) method. Hyperfine structure constants, isotope shift and Landé gJ factors are computed for the 2s22p,2s2p2 and 2p3 levels. The contribution of the Breit interaction and QED effects, mainly self-energy and vacuum polarization corrections, on these levels is also investigated. The uncertainties in the lifetimes and line strengths are computed, and transitions are classified according to the NIST accuracy nomenclature. A comparison with the previously available results is also carried out. This study provides extensive results for B-like Xe49+, which are useful for plasma diagnosis.

Development of interference-free rotational and vibrational thermometry for studies on shock-heated thermochemical non-equilibrium CO

A mid-infrared interference-free laser absorption technique for simultaneously measuring rotational temperature, vibrational temperature, and CO concentration was developed for application to shock-tube studies on thermochemical non-equilibrium CO over 1000–3000 K. Three transition lines in the fundamental vibrational band of CO (P(0, 21), near 4.87 μm, P(1, 21), near 4.93 μm, and P(0, 37), near 5.05 μm) were selected. The P(0, 21)/P(1, 21) line pair was used for vibrational temperature measurements whereas the P(0, 21)/P(0, 37) line pair was used for rotational temperature measurements. Spectroscopic parameters for developing the technique were measured: line strengths and collisional broadening data in Ar were obtained at 1040–2940 K. Validation experiments for the thermometry system were performed in shock-heated thermal-equilibrium CO/Ar mixtures at 1050–3010 K and 1.1–2.8 bar. The time-dependent rotational and vibrational temperatures were measured during the vibrational relaxation processes of CO. The technique showed high sensitivity in detecting the rotational and vibrational temperatures. The measured rotational temperature agreed well with the temperature calculated using the measured pressure and isentropic relationship. The measured vibrational temperature showed good agreement with the predictions using the Landau and Teller theory and Millikan and White relationship. The time-dependent CO concentration during the oxidation processes of n-heptane over a wide temperature range (1350–2750 K) was measured considering n-heptane as one of the alternative fuels for the scramjet. The interference-free laser absorption strategy showed good flexibility in detecting the CO concentration at ultra-high temperatures. The measured results showed overall good agreement with the predictions from two detailed mechanisms and one skeletal mechanism. The reactivity of n-heptane was found to be insensitive to the temperature increase at ultra-high temperatures (>2100 K).

Comparative line position and line strength analysis of the [formula omitted] dyad of [formula omitted] and [formula omitted

A highly accurate ro-vibrational analysis of FTIR spectra (line positions of 13CD4 and line strengths of both the 12CD4 and 13CD4 species) is presented. The high-resolution infrared spectra of both molecules were measured with a Bruker IFS125 HR Fourier transform infrared spectrometer at an optical resolution of 0.003 cm−1 and analyzed in the regions of 800–1400 cm−1 where the ν2/ν4 dyad is located. The number of 901 transitions with Jmax=23 were assigned to the ν4 and ν2 bands of 13CD4 (this number is about 5.3 times higher in comparison with the number of known assigned transitions for 13CD4). The weighted fit of experimental line positions was made using the Hamiltonian model which takes into account the resonance interactions between the (0001,F2) and (0100,E) vibrational states. As a result, set of 18 fitted parameters of the (0001,F2)/(0100,E) vibrational states of 13CD4 was determined which reproduce the initial 901 experimental ro–vibrational line positions with the drms=2.59×10−4 cm−1, which is close to the experimental uncertainty of the recorded spectra and about 1330 times better in comparison with the reproduction of the same line position values by the use of parameters from Loëte et al. (1983). The analysis of 1557 experimental lines of the dyad of 12CD4 and 131 lines of the dyad of 13CD4 was fulfilled with the Hartmann–Tran profile to simulate the measured line shape and to determine experimental line intensities. Sets of 6/1 varied effective dipole moment parameters of 12CD4/13CD4 are determined which reproduce the initial 1557/131 line strengths with the drms=4.80% and 4.21%. Lists of the assigned line positions and strengths in the studied region are presented as the Supplementary data to this paper.

Mean Lifetimes of ns, np, nd, &amp; nf Levels of N V

Nitrogen is one of the key elements in the evolution and formation of stellar objects. Earth's atmosphere contains 21% oxygen and 78% nitrogen; these two gases give rise to aurora when ions of the solar wind in the ionosphere collide with them. Some aerosols made of nitrogen and oxygen are also found in the atmosphere. Nitrogen, hydrogen, carbon, and oxygen are the main contributors to the origin of life on Earth. The spectrum of nitrogen ion (N V) has been studied using Quantum defect theory (QDT) and Numerical Coulombic approximation (NCA). N V has two electrons in the core, with the nucleus, and one electron outside the core. It makes it hydrogen or lithium-like. In the first part, the energies of the ns, np, nd, and nf up to n &lt; 30 were calculated with the help of QDT. In the second part, the wavelengths were calculated using the energies and line strength parameters using NCA. Very little experimental data on lifetime and transition probability are available; however, Biemont et al. have calculated the lifetime of the 48 levels of N V using coulomb approximation. In this study, we calculated the lifetime of 196 multiplets of N V. The results are compared with the available experimental and theoretical lifetimes; an excellent agreement was found between known lifetimes and calculated in this work. The lifetimes of 100 multiplets are presented for the first time. The lifetimes of each of the Rydberg series of N V were fitted, and a third-degree polynomial represents the lifetimes of each series.

Analysis of Weld Lines in Micro-Injection Molding.

Micro-injection molding (µIM) is a widespread process for the production of plastic parts with at least one dimension, or feature, in the microscale (conventionally below 500 µm). Despite injection molding being recognized as a robust process for obtaining parts with high geometry accuracy, one last occurrence remains a challenge in micro-injection molding, especially when junctions are present on the parts: the so-called weld lines. As weld lines are crucial in determining mechanical part performances, it is mandatory to clarify weld line position and characteristics, especially at the industrial scale during mold design, to limit failure causes. Many works deal with weld lines and their dependence on processing parameters for conventional injection molding, but only a few works focus on the weld line in µIM. This work examines the influence of mold temperature on the weld line position and strength by both experimental and simulation approaches in µIM. At mold temperatures below 100 °C, only short shots were obtained in the chosen cavity. At increased mold temperatures, weld lines show up to a 40% decrease in the whole length, and the overall tensile modulus doubles. This finding can be attributed to the reduction of the orientation at the weld line location favored by high mold temperatures. Moldflow simulations consistently reproduce the main features of the process, weld line position and length. The discrepancy between experimental and simulated results was attributed to the fact that crystallization in flow conditions was not accounted for in the model.

Spectroscopic Properties Including Line Strengths, Wavelengths, and Transition Probabilities for Hf LXII

Spectroscopic Properties Including Line Strengths, Wavelengths, and Transition Probabilities for Hf LXII

LIBS at high duty-cycles: effect of repetition rate and temporal width on the excitation laser pulses

Laser-induced breakdown spectroscopy (LIBS) is becoming a more mature technology every year with new variants such as laser ablation molecular isotopic spectrometry, reheating by various discharge techniques, and multiple pulse excitation schemes, in which sometimes lasers of different pulse lengths are used. However, lasers with inherent parameters like pulse length and repetition rate are still almost exclusively employed. Recent years have witnessed the advent of novel high-repetition-rate laser concepts for machining processes, like welding, milling, and engraving. Here, a comprehensive study of single-pulse LIBS spectra of a single aluminum target is presented to showcase the applicability of flexible high duty-cycle master oscillator power amplifier (MOPA) lasers. Although traditional flashlamp-pumped Fabry–Pérot lasers only permit a variation in the pulse energy and are operated at very low duty-cycles, MOPA lasers add repetition rate and pulse length as variable parameters. A thorough analysis of the temporal plasma behavior revealed the emission dynamic to closely match the excitation laser pulse pattern. An aluminum sample’s spectral response was shown to be significantly impacted by variations in both rate and length. Although the spectral emission strength of the elemental lines of Al, Sr, and Ca all peaked at slightly different parameter settings, the strongest impact was found on the relative abundance of molecular AlO bands. Unlike in previous laser ablation molecular isotopic spectrometry (LAMIS) publications, the latter could be readily detected with a good intensity and well-resolved spectral features without any temporal gating of the detector. This finding, together with the fact that MOPA lasers are both inexpensive and dependable, makes for a promising combination for future studies including the detection of diatomic band structures.

Statistical Prediction of [CII] Observations by Constructing Probability Density Functions Using SOFIA, Herschel, and Spitzer Observations

We present a statistical algorithm for predicting the [CII] emission from Herschel and Spitzer continuum images using probability density functions (PDFs) between the [CII] emission and continuum emission. The [CII] emission at 158[Formula: see text][Formula: see text]m is a critical tracer in studying the life cycle of interstellar medium and galaxy evolution. Unfortunately, its frequency is in the far-infrared (FIR), which is opaque through the troposphere and cannot be observed from the ground except for highly red-shifted sources ([Formula: see text]). Typically [CII] observations of closer regions have been carried out using suborbital or space observatories. Given the high cost of these facilities and limited time availability, it is important to have highly efficient observations/operations in terms of maximizing science returns. This requires accurate prediction of the strength of emission lines and, therefore, the time required for their observation. However, [CII] emission has been hard to predict due to a lack of strong correlations with other observables. Here we adopt a new approach to making accurate predictions of [CII] emission by relating this emission simultaneously to several tracers of dust emission in the same region. This is done using a statistical methodology utilizing PDFs among [CII] emission and Spitzer IRAC and Herschel PACS/SPIRE images. Our test result toward a star-forming region, RCW 120, demonstrates that our methodology delivers high-quality predictions with less than 30% uncertainties over 80% of the entire observation area, which is more than sufficient to test observation feasibility and maximize science return. The pickle dump files storing the PDFs and trained neural network module are accessible upon request and will support future FIR missions, for example, GUSTO and FIR Probe.

Improved Theory of the Effective Dipole Moments and Absolute Line Strengths of the XY2 Asymmetric Top Molecules in the X2B1 Doublet Electronic States.

A new effective dipole moment model for the XY2 (C2v-symmetry) molecule in a doublet electronic state is derived that includes (as special cases) all currently known models of effective dipole moments for such types of molecules, and allows us to take into account the influence of spin-rotation interactions on the effective dipole moment operator that were not considered in the preceding studies. Necessary for the analysis of absolute line strengths, the matrix elements of this dipole moment operator are derived. A comparison with the previous analog models is made and discussed. The efficiency of the obtained results is illustrated, which have been applied to a set of the "forbidden" ΔKa=2 transitions of the ν3 band of the OClO free radical molecule.

Fully relativistic many-body perturbation energies, transition properties, and lifetimes of lithium-like iron Fe XXIV

Employing the advanced relativistic configuration interaction (RCI) combined with the many-body perturbation theory (RMBPT) method, we report energies and lifetime values for the lowest 35 energy levels from the (1s2)nl configurations (where the principal quantum number n = 2–6 and the angular quantum number l = 0,…,n–1) of lithium-like iron Fe XXIV, as well as complete data on the transition wavelengths, radiative rates, absorption oscillator strengths, and line strengths between the levels. Both the allowed (E1) and forbidden (magnetic dipole M1, magnetic quadrupole M2, and electric quadrupole E2) ones are reported. Through detailed comparisons with previous results, we assess the overall accuracies of present RMBPT results to be likely the most precise ones to date. Configuration interaction effects are found to be very important for the energies and radiative properties for the ion. The present RMBPT results are valuable for spectral line identification, plasma modeling, and diagnosing.

S-type Stars: Line List for the A2Π–X2Σ+ Band System of LaO

LaO bands are found in the spectra of cool S-type stars. The bands of the A2Π–X2Σ+ transition with and v″ ≤ 4 are rotationally analyzed, providing spectroscopic constants for the A2Π state. Line strengths are calculated using an ab initio transition dipole moment function, and radiative lifetimes for the A2Π state have also been computed. A line list for the A2Π–X2Σ+ transition of LaO is provided and can be used to determine LaO stellar abundances.

Minor Mergers Are Not Enough: The Importance of Major Mergers during Brightest Cluster Galaxy Assembly

We investigate the roles of major and minor mergers during brightest cluster galaxy (BCG) assembly using surface brightness profiles, line indices, and fundamental plane relations. Based on our own sample and consistently reanalyzed Sloan Digital Sky Survey data, we find that BCGs and luminous normal ellipticals (LNEs) have similar central velocity dispersions, central absorption line strengths, and central surface brightnesses. However, BCGs are more luminous due to their much larger radial extent. These properties result in a flattening of the Faber–Jackson and Mgb–luminosity relations above 1010.6 . We use this effect to estimate an amount of 60%–80% of accreted and merged light in BCGs relative to LNEs, which agrees with results from cosmological simulations. We determine the contribution of this excess light (EL) at each radius from the difference between the surface flux profiles of BCGs and LNEs. It is small in the center but increases steeply to 50% at ∼3 kpc radius. The shape of these profiles suggests that BCGs could be formed from LNEs in three major merger processes. This is also consistent with the mild increase of the Sérsic indices from n ≈ 4 to n ≈ 6, as confirmed in merger simulations. We note that minor mergers cannot be the dominant origin of the BCG’s EL because they deposit too few stars at intermediate radii r ≲ 20 kpc. The shape of the EL profile also explains a detected offset of 0.14 dex of the fundamental planes for BCGs and LNEs relative to each other.